Angus Moat, brother of gunman Raoul Moat who died after being cornered by police following several shootings. Photograph: Christopher Thomond for the Guardian

Angus Moat hadn't seen his younger brother for nearly seven years when two weeks ago, on 4 July, a friend rang him up at home. Had he listened to the radio? No. Was Raoul Moat his relative? "And I'm thinking, 'Ah no, what's he done now?'" It wasn't that he knew of trouble before — he had no idea, for example, that Raoul had just spent time in prison — it was more the way Raoul's life had developed – the friends he had made, the macho culture of bodybuilding, the nightclub bouncing. "I always knew there was the potential for him to get into some kind of trouble, and I just thought, 'What's going on here now?'" Angus's face, already set in a frown, contracts even further with tension and dismay.

The next day he went to work, deciding, early on, not to hide from his colleagues – Moat is a tax officer, specialising in compliance and education – that, yes, this was his brother. By mid-week the manhunt was in full swing. It was becoming harder to keep himself out of the unholy matrix of press and police and general public that builds so fast around such a crime, and in this case, weeks after Derrick Bird's rampage in Cumbria, it built especially fast. On Wednesday a visit to the local pub with friends quickly became, for Angus, a particularly 21st century kind of ordeal.

"It had big screens up – and he keeps flashing up on the screen, my brother on the big screens. Obviously, they used the most unflattering photograph they could possibly find. The press was winding up into a frenzy about whether my brother was an evil man, bogeyman, cartoon character Terminator-type person, and I'm sitting there thinking, 'This is not right – they're all taking in what's on the screen, but there's always two sides to everything, at least.'"

In the days since his brother's death Angus has taken it upon himself to put the possibility of two sides to anyone who asks, with a kind of reckless rearguard loyalty to his only brother that he would be the first to admit is coloured by guilt – guilt at them having drifted so far apart, guilt that he didn't know his brother was in trouble, that he didn't do anything. He makes no excuse – he knows there is no excuse – for what his brother did. But his is a desperate search for explanations, conducted in the teeth of the dominant narrative – on leaving prison, where he was serving time for assault of a family member, Raoul Moat shot and wounded his ex-girlfriend, killed her new partner, and then shot a policeman, who is now blind: maybe the police were harassing him ("I'm not saying it was official Northumberland police policy, but all you need is a couple of police officers with a grudge and they can make life absolutely hell for somebody"); after his attack on PC Rathband "[Raoul] was a dead man walking". Angus also suggests that portrayals of Raoul as domestically violent and controlling may not be fair – "obviously you don't know what's going on between two partners in a relationship – nobody does. But that was something I never noticed in him".

At first, however, he refused to talk to the press at all, and by late Thursday was on the run from them. He moved from friend's house to friend's house; he rejected offers of money. "I had to leap out of the bathroom window once and send my friend out the door as a decoy. It was almost like I was in a parallel fugitive situation."

They had got to his mother, too, and though he alleges she and his stepfather had agreed not to talk, his stepfather was out, and she talked to tabloid journalists and provided them with photographs, "snapshots taken from my childhood, which she's now ruined – I can never see those photographs again, because they'll be linked into this as opposed to the childhood memories, and she basically went on the record saying that Raoul was better off dead. I'll never speak to her again for that. I'm thinking if he's on the run and he's already got issues with his family, and she's one of the major reasons why, because she was a really, really bad parent" – he alleges that he received no maternal affection, that she was abusive emotionally – " but, I remind him, your mother is ill – "If I wasn't involved with this first-hand I'd say it was despicable that a mentally ill woman was harangued into handing over these photographs. I don't really think that's what's happened." On the contrary, Angus thinks his mother knew what she was doing. I personally think she should be burnt at the stake for what she said to the press. That's what they [used to] do with witches. I'm not denying that she's got a mental disorder, but has been malicious and vindictive."

Although Angus says he struggles to remember many happy times with his mother, he pinks with unshed tears when asked the same question about his brother, who was three years younger: games on the beach, the ducks Raoul raised from eggs, in the back garden, amusing episodes of defiance against the neighbours, the pranks at birthdays in their early 20s. The brothers had different fathers, but neither was told who they were. Raoul made it very clear, in his last stand in Rothbury, that this was something he cared a great deal about, and, even though Angus understands that the 70s were different, that there was far more stigma about babies born out of wedlock, his fury at the situation arrives almost on the same breath.

"I feel very strongly that a child has a right to know who his father is. I don't think a selfish woman has a right to have a baby as her own plaything. I think there are massive indications there for somebody's identity in adult life. We weren't given the opportunity, for what I believe to be very selfish reasons." He has since discovered who his own father is, though he has no intention of contacting him; apparently, after all the publicity, someone has turned up claiming to be Raoul's. "I think it's a crying shame he's only turned up now Raoul's dead. It's a bit late in the day."

Then there was his mother's illness, which he first became aware of when he was about seven. "She was coming out with all this religious mumbo-jumbo – 'we are the chosen people and you're going to be princes and you'll have crowns and don't be sad because the devil doesn't want you to be sad.' When you're seven years old you believe what adults tell you, but even at seven I was thinking, this is crazy. And I was crying my eyes out about it – I was very upset. Two years later she had another [episode] and I thought 'yeah, you're full of shit.' Sorry I'm being a bit crude there, but – " he is speaking extremely fast now. "It was very troublesome and traumatic. My mum was absent a lot of the time in mental hospitals. And often at home she was knocked out on medication. So you basically got a zombie or an absent mother. It's not a good position to be in. My grandma had to be there for us – and she was. She did a very good job." So was it your mother who made you both so angry? "Well, all through my life I've been called Angry Angus – it's just what my friends call me." A brief, strangled laugh. "My nickname's Anguish, bizarrely. Yeah, it made me angry. I'm always angry. I'm still angry. I'm just not as angry as Raoul."

When he was 14 and Raoul 11 his mother married, but while Angus and Brian Healey got on, parental inexperience and a clash of temperaments meant that the new stepfather and Raoul did not. There were episodes of harshness ("Scruff of the neck against the wall kind of thing – not nice stuff. In later years I think he's quite a decent guy, but I don't think he was doing the right thing then.") His mother has said the tension between the men was very difficult to live with, and that it contributed to her estrangement from Raoul when he was 19, but Angus believes that their mother's poor mental health also took its toll on the relationship.

The brothers' separation began when their grandmother died. "It's really sad, because one of the last things my gran said was 'Will you two stay together.' But we drifted after that. I went off to Nottingham, to uni and stuff" – he already had a first degree from Newcastle University in politics and research methods for public policy; Nottingham was for a masters degree – "Maybe if I'd made a more empathetic effort to keep in touch with him after that maybe something might have been different." Raoul became more embedded in a different kind of life, made friends who Angus had nothing in common with, had his first child – and, about 10 years ago, made a suicide attempt. (Later Raoul seems to have had enough self-knowledge to know when he needed help: a couple of days ago a friend gave tapes to ITV that revealed he asked to be referred to a psychiatrist last year. Nothing was done.)

Angus visited him in hospital, "but to be honest he was so preoccupied with his girlfriend, who was the mother of his daughter, I felt it really isn't my place to be here, so I better say farewell – my nose was a bit put out of joint by it actually. I felt a bit hurt, because I'd turned up to try and make sure my brother's OK." About five years ago Angus says he suffered his own mental crisis, triggered by a girlfriend leaving him, two friends committing suicide and trouble at work; six months of therapy and two years of anti-depressants brought him back onto an even keel.

It was around that time that he last saw his brother alive – "I passed him in the street and said hello" – which is presumably one of the reasons why the police refused to let him cross the cordon and try to speak to his brother when Raoul eventually came out of hiding, a decision of which he is extremely critical. He is also critical of what seems like a particularly unfortunate kind of incompetence: having been unable to get through on the phone, he flagged down a police car to tell them he was Raoul's brother. He says they asked him various questions to test whether this was true, but he alleges the information they had was from inaccurate press reports. He was eventually put through to a superior.

"So I returned back to the house, and had to watch it on television. It was horrific. I'm powerless to do anything about it. I'm thinking 'I really hope they arrest him and treat him' – in this country we arrest people and we try them. We don't put them into a summary execution position. So I'm watching this and it's getting worse. If he was going to go out in a blaze of glory there's forest and cliffs and crags and rocks and caves [near Rothbury], it would have been a shoot-out somewhere like that. But he was tired, dejected, sitting on a river bank, looking very sorry for himself, looking devastated, giving himself up."

When shots were finally fired an ambulance arrived to take him away.

"Turns out he was probably dead at the site, but they didn't announce that, for 45 minutes. So I had to sit in front of the TV, watching an ambulance drive through the night with my brother in it, who was already dead, thinking, 'I hope he's not dead, I really hope he's not dead."

How did he react? "Complete disbelief. Crying my eyes out. Throwing up. Delirium. Nearly broke my hand punching the floor out of sheer frustration. It was the most horrific thing – I wouldn't wish it on anybody. My loved brother. Killed on TV. "

Six hours later a reporter from the News of the World contacted Angus. "I had uniformed police at the front of my flat, because I warned them – I basically said you better keep the press away from me, because I won't be responsible for my actions. So they put two uniformed officers in front of my flat, to keep the press away."

Ironically, a newspaper reporter put him in touch with his uncle, Charlie Alexander, with whom he is now gratefully staying, and with whom he intends to complain to the IPCC.

Angus says he has no time for those who, on Facebook and elsewhere, think his brother is an anti-establishment "legend". "I do not condone that at all, and I'm sure he wouldn't either if he was still here. People who celebrate the bravado to give some kind of outlet to the negative side of their feelings and their emotions and their lives."

Sympathy, empathy – these are very ambivalent things, given the magnitude of Raoul's crime– grieving for him must be more complicated again. "Oh absolutely. I'm furious with him for what he's done. But I'm heartbroken at the same time. I'm defending him, because I think I will defend him – I love him, he's my brother – but he's a bête noir as well. I accept what he did was wrong, but I would rather have seen an outcome where he was arrested and sentenced and treated accordingly, rather than an execution on a hillside. But to die on that bank, suicidal and lonely – it broke my heart."